# set 无序
print(type({1,2,3,4,5,6,2}))
print(len({1,2,3,4,5,6,2}))
print({1,2,3} - {1,4,5,6})  #求差集
print({1,2,3} & {1,4,5,6})  #求交集
print({1,2,3} | {1,4,5,6})  #求并集
print(type(set()))  #{}是字典类型dict